The present invention relates to regulating a railway vehicle.
The problem of railway vehicle regulation is a system-wide problem but can be considered as being the sum of a large number of single journeys for each individual vehicle in a railway. In overall terms, it amounts to a balance between the cost of running railway vehicles and providing a service considered as acceptable to the public. A service which is generally regarded as acceptable is one which provides frequent railway vehicles (i.e. with short headways) as well as short journey times, and these are conflicting requirements.
The trade-off between these two requirements is simple on a plain line track with equally spaced stations, but real railways are not like this. The present invention aims to provide means to overcome the problems associated with railway vehicle regulation on non-ideal railways.
Systems exist at present where running profiles are predefined at the signalling system design stage. These systems offer only two different running profiles, one providing minimum journey time and one providing power savings utilising coasting, which increases journey time by a fixed percentage (usually chosen to be between 5% and 10%). It is possible to select between these profiles but they cannot be changed without considerable effort since they are "hard wired" typically in programmable read-only memories. Special station approach profiles can also be configured at the design stage but these generally provide only one crudely defined approach profile at a lower than usual speed. This speed is either implemented as a permanent speed restriction through a station (which delays railway vehicles unnecessarily on clear track) or as a selectable reduction in target speed (which is chosen from a limited range of available target speeds) on the approach to a station.
It is known that there are many different speed profiles which can be adopted in order for a railway vehicle to travel between two points on a track. There are three characteristics of such profiles that are important in the transport industry. They are "journey time" (how long it takes to get from one place to another), "headway" (the time interval between one railway vehicle and the next) and "power consumption" (how much energy is used in the Journey).
By the nature of physics relating to a journey, optimising all three of these at once is not possible. Curves representing an optimised running profile for each of these are shown in FIG. 1.
Each curve can be described in the following way:
i) For "Minimum Journey Time", the profile uses maximum acceleration and maximum service braking between maximum safe speed (as defined by permanent and temporary speed restrictions) and stopping points (either station stops or limits of movement authority). PA1 ii) For "Best Power Consumption", the profile uses maximum acceleration to maximum line speed and then coasts at some point. It approaches the station stop using maximum service braking. PA1 iii) For "Minimum Headway", the profile uses maximum acceleration to maximum line speed, approaches all speed restrictions using maximum service braking and adopts a special shallow approach to the limit of its movement authority or required stopping point (e.g. station). The actual form of the station approach is the subject of simulation studies.
The fine details of these profiles depend on things such as the length of the railway vehicle, the braking and acceleration capabilities of the railway vehicle and any speed restrictions applying to the railway vehicle. These are different for each type of railway vehicle and it is logical to enable each railway vehicle to have information relating to these characteristics.